High risk of abnormal QT prolongation in the early morning in diabetic and non-diabetic patients with severe hypoglycemia

Abstract

Background. Several studies have suggested that the occurrence of severe hypoglycemia during sleep may be more dangerous for cardiac arrhythmia than that in the day-time.

Methods. We performed a retrospective study between January 2006 and March 2012 to assess electrocardiograms during severe hypoglycemia in patients with or without diabetes.

Results. A total of 59,602 patients who visited the emergency room by ambulance were screened, and 287 patients with severe hypoglycemia were enrolled. The median blood glucose levels in patients with (DM, n = 192) and without diabetes (non-DM, n = 95) were 30 and 45 mg/dL, respectively. During severe hypoglycemia, the incidence of abnormal QT prolongation was significantly higher in the early morning (4–10 a.m.) than at other times (DM group, 74.3% versus 54.1%, P = 0.02; non-DM group, 78.3% versus 50.0%, P = 0.01). Multivariate logistic regression analysis identified the occurrence of severe hypoglycemia in the early morning as a strong factor for abnormal QT prolongation (DM group, odds ratio [OR] 2.80, 95% confidence interval [CI] 1.15–6.80, P = 0.02; non-DM group, OR 4.53, 95% CI 1.30–15.74, P = 0.01).

Conclusions. The incidence of abnormal QT prolongation during severe hypoglycemia was significantly higher in the early morning than at all other times, independent of the cause of severe hypoglycemia.

Key words::

• Arrhythmia
• diabetes
• nocturnal hypoglycemia
• QT prolongation
• severe hypoglycemia

Acknowledgements

T.T. conceived the study. T.T., M.Ka., and M.N. designed the protocol. T.T., R.Y.-H., H.K., M.Ki., R.H., and A.K. contributed to the data collection and preparation. T.T., R.Y.-H., M.Ki., H.N., and M.N. analyzed the data. T.T., R.Y.-H., M.Ka., and M.N. wrote the report. All authors contributed to the interpretation of the results and approved the final version of the manuscript. T.T. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Funding: This work was supported by JSPS KAKENHI [grant number 26860701].

Declaration of interest: The authors have no potential conflicts of interest relevant to this article to report.